Data Transmission Using a Standard Connection S5-95U, SINEC L2
Structure of the Receive Coordination Byte (CBR)
Figure 4-7 shows the structure of the receive coordination byte (CBR).
Figure 4-7. Structure of the Receive Coordination Byte (CBR) for a Standard Connection
R RRW/R
7 6 5 4 3 2 1 0
CBR
Bit
a
a
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!
Warning
If you write in bit 6 of CBS, the bus might enter an undefined state.
Bit 6 is not available to the user.
R: Read only
W/R: Write / read
Reserved bit
a
a
a
a
a
a
0: No error
1: Error during the last data transmission
(Bits 2 and 5 describe the error cause in more
detail.)
0: No error
1: Receive mailbox error (The DB is not
available.) Received data stay stored. A new
receive request can transfer the received data
to the receive mailbox once the error has been
corrected.
0: The L2 interface is not overloaded.
1: The L2 interface is overloaded.
0: The user program can access the receive
mailbox. (The operating system has no access
to the receive mailbox.)
1: The operating system can accept data in the
receive mailbox. (The user program has no
access to the receive mailbox.)
4-8
EWA 4NEB 812 6112-02
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